think outside the
box

an automatic apparatus, the internal operations of which are mysterious to non-experts.

Black does not refer to the colour of the device but to the arcane nature of its functions. Originally Royal Air Force slang for a navigational instrument in an aircraft, the phrase is now used in aviation specifically to refer to the flight recorder.

box clever

act so as to outwit someone - British informal

1950 - Alexander Baron - There's No Home - If you box clever and keep your mouth shut... you ought to be able to count on a suspended sentence.

be a box of birds

be fine or happy - Australian & New Zealand

a box of tricks

an ingenious gadget – informal

in the wrong box

placed unsuitably or awkwardly

in difficulty or at a disadvantage

This phrase perhaps arose with reference to an apothecary's boxes, from which a mistaken choice might have provided poison instead of medicine.

out of the box

unusually good - Australian & New Zealand informal

out of your box

intoxicated with alcohol or drugs - British informal

a Pandora's box

a process that once begun generates many complicated problems.

In Greek mythology, Pandora was the first mortal woman. One story recounts that she was created by Zeus and sent to earth with a box or jar of evils in revenge for the fact that Prometheus had disobediently given the gift of fire to the earth. She let all the evils out of the container to infect the earth.

Only hope remained to ease the lot of humankind. In another account, the box contained all the blessings of the gods which, with the exception of hope, escaped and were lost when the box was opened.

1997 Spectator Drummond's series has opened a Pandora's box of complaints about the tide of mediocrity engulfing the art.